Apparatus for indicating the breakage of warp threads in a loom

ABSTRACT

A stationary contact bar of U-shaped cross-section with the open side of the U directed upwardly extends crosswise of a loom. A reciprocating insulative support bar is disposed to extend with clearance into the opening between the limbs of the cross-section of the stationary bar and to extend above those limbs. A reciprocating contact bar having teeth formed thereon is affixed to the support bar above those limbs, and a plurality of drop wires having the shape of apertured plates are engaged over these bars to fall into bridging contact between the two contact bars upon breakage of warp threads threaded through those drop wires.

[451 Sept. 23, 1975 United States Patent [191 Pfarrwaller 2,556,332 6/1951 Meadows, Jr et 139/353 3,246,091

INA

3,635,258 Powell 139/368 [75] Inventor: Erwin Pfarrwaller,Winterthur,

Switzerland Primary Examiner-Mervin Stein Assistant Examiner-Steven Hawkins [73] Assignee: Sulzer Brothers Limited, Attorney, g or Firm-P6nfli6 & dm nd Switzerland [57] ABSTRACT A stationary contact bar of U-shaped cross-section with the open side of the U directed upwardly extends crosswise of a loom. A reciprocating insulative support bar is disposed to extend with clearance into the [22] Filed: July 15, 1974 [21] Appl. No.: 488,794

[30] Foreign Application Priority Data July 24, 1973 Switzerland.......................... 010763 opening between the limbs of the cross-section of the stationary bar and to extend above those limbs. A re- [52] US. 139/353; 139/368 ciprocating contact bar having teeth formed thereon is Int. D03D 51/20 affixed to the support bar above those limbs, and a Field of Search................:::.

plurality of drop wires having the shape of apertured ZOO/61.18

plates are engaged over these bars to fall into bridging contact between the two contact bars upon breakage of warp threads threaded through those drop wires.

3 Claims, 2 Drawing Figures R f r F APPARATUS FOR INDICATING THE BREAKAGE F WARP THREADS IN A LOOM This invention relates to warp I stop motions for looms, i.e. to apparatus for detecting the breakage of warp threads in a loom and for arresting the operation of the loom in consequence thereof. The invention relates more particularly to the contact bars in such apparatus by means of which a signal may be produced in the event of a warp thread breakage. In typical apparatus of this character, there are provided ;two contact bars extending across the width of the loom and a number of drop wires, one hanging on each warp thread. Upon the breakage of a warp thread, the associated drop wire will fall and complete-an electrical circuitbetween the two contact bars, and the completion of this circuit may be employed to stop the loom.

Apparatus of this general character is shown in US. Pat. Nos. 2,814,088 and 2,844,860 Swiss Pat. No. 430,61] shows such apparatus in which one of the contact bars is of U-shaped cross-section, the other bar taking the form of a narrow. flat plate which is sup-- ported between the limbs of the cross-section of the U- shaped bar for reciprocation crosswise of the loom, the second bar being insulated from the first by means of plates or sheets of insulating material. This construction involves wear between the reciprocating contact bar and the plates which insulate it from the contact bar of U-shaped cross-section, and the requirement for insulating material entails a large width for the contact bar arrangement which must be straddled by the drop wires.

According to the present invention, apparatus for detecting the breakage of warp threads in a loom comprises an electrically conductive first or carrier bar of U-shaped cross-section, an electrically insulating support bar which is housed partly within the carrier bar and which has one longitudinal edge located beyond the free ends of the legs from the bight of the U, and an electrically conductive finder bar mounted on that longitudinal edge of the support bar, no part of the exposed surface of the finder bar being as close to the bight of the U as the free ends of the legs of the U.

Because no part of the finder bar lies between the legs of the U-shaped cross-section of the carrier bar, the thickness of the finder bar is not dictated by the need to provide adequate insulation between the carrier bar and the finder bar. Instead, it is only necessary to provide a sufficient vertical spacing between the carrier bar and the finder bar to insure adequate insulation. The thicknesses of the finder bar and the support bar, measured in the direction normal to their length and to the legs of the U cross-section of the carrier bar, may be substantially equal.

Because of the freedom in selecting the thickness of the support and finder bars, it is possible to design the contact bar system to be thin enough to be used with standard drop wires, even if the legs of the carrier bar are made comparatively thick.

The support bar and finder bar may be mounted for movement together in the direction of their length. Preferably the contact bar system includes power means arranged to reciprocate the support bar and the finder bar. This makes it easier to locate a broken warp yarn, since the fallen drop wire and those on either side of it will be reciprocated slightly. I

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described in terms of a presently preferredexemplary embodiment and by reference to the accompanying drawings, in which:

FIG. 1 is a vertical sectional view through the bars of one form of apparatus according to the invention for indicating thebreakage of warp threads in a loom, the bars being shown in conjunction with a drop wire which is seen in fragmentary elevation; and

FIG. 2 is a fragmentary side elevation shown at a reduced scale of the bars of the embodiment of FIG. 1, in combination with a fragmentary schematic showing of a loom and of means to reciprocate the support and finder bars of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIG. 1, metallic carrier bar 1 of U- shaped cross-section is adapted to extend across the width of a loom, and in use is fixed at its ends to the frame 10 of the loom, as indicated at 10 in FIG. 2. A support bar 5 which is made of an electricallyinsulating material also extends across the width of the loom, with its lower part between the legs 7 of the cross-section of the carrier bar 1. The support bar can be reciprocated transversely of the loom by an electric motor 1] driving through an eccentric or other suitable linkage, which may be of known type. A clearance 8 is left between the inside surfaces 6 of the carrier bar 1 and the surfaces of the support bar 5 to allow reciprocation. A metallic finder bar 3 which has teeth 2 along its top edge is fixed to the support bar 5 along the top of the latter. A tongue and groove joint is formed between the support bar and the finder bar, the sides of the groove being indicated at 4. The distance between the finder bar 3 and the carrier bar 1 is nowhere less than the distance d, which may for example be 5 mm.

Each of the warp yarns of the loom passes through an associated drop wire 13 which is engaged over or surrounds the carrier bar 1, the support bar 5 and the finder bar 3. Consequently, when a warp yarn breaks and the corresponding drop wire 13 has dropped into the chain-dotted position 13a of FIG. 1, the drop wire 13 touches the bar 3 at 21 and the bar 1 at 22, so that an electrical connection is made between the electrical leads 14 and 15. This connection may be employed to stop the loom.

When the finder bar 3 is reciprocated in the direction indicated by a double arrow 19, the drop wire 13 associated with the broken warp will have dropped into the space 23 between two teeth, and will be likewise reciprocated. Consequently, the drop wires which are adjacent to the dropped drop wire and which are hanging on undamaged warp yarns are reciprocated slightly so that the machine attendant can see the position of the broken yarn.

Since only the finder bar 3 and its support bar 5 are reciprocated whereas the carrier bar 1 remains station ary, the other drop wires which are associated with unbroken warp yarns cannot participate in the movement, as might happen because of friction on the outside surfaces 16 of the carrier bar 1 if the carrier bar reciprocated. Because of the clearance 8, there is little friction on the surfaces 17 of the support bar 5 when reciprocating, and so wear is slight. The support bar 5 has a thickness f no greater than the thickness of the finder bar 3, and so the overall thickness a of the carrier bar 1 can be small even though its legs 7 can have a relatively large thickness [2. The bar 1 can therefore have relatively high bending strength, so that the contact bar system is of use for large cloth widths, e.g. of meters or more.

The relatively large vertical space d between the bars 1 and 3 insures minimal capacitive coupling between the bars 1 and 3; excessive coupling might lead to interference which could cause unnecessary stoppages of the machine when operating on an AC. supply, for example, a 60 Hz. supply. Also, there is no risk of a false electrical connection occurring between the bars 1 and 3 and causing unnecessary stoppages of the machine as might happen if part of the finder bar 3 extended between the legs of the carrier bar 1, and were to become covered with moist fluff.

While the invention has been described hereinabove in terms of a presently preferred embodiment thereof, the invention itself is not limited thereto but rather comprehends all modifications of and departures from that embodiment properly falling within the spirit and scope of the appended claims.

I claim:

1. Apparatus for indicating the breakage of a warp thread in a loom, said apparatus comprising an electrically conductive bar of U-shaped cross-section extending crosswise of the loom, an electrically insulative support bar extending parallel to and disposed partly within the U-shaped cross-section of said first-named bar, said support bar further extending exteriorly of said cross-section with one longitudinal edge of said support bar being outside said cross-section, and an electrically conductive bar affixed to the support bar along said one longitudinal edge and being in its entirety outside said cross-section.

2. Apparatus according to claim 1 wherein said lastnamed conductive bar is provided with teeth, said apparatus further including means to reciprocate the support bar and last-named conductive bar crosswise of the loom.

3. Apparatus according to claim 1 in which the support bar and last-named conductive bar have substantially the same thickness in directions transverse of their length and of the legs of said U-shaped crosssection. 

1. Apparatus for indicating the breakage of a warp thread in a loom, said apparatus comprising an electrically conductive bar of U-shaped cross-section extending crosswise of the loom, an electrically insulative support bar extending parallel to and disposed partly within the U-shaped cross-section of said firstnamed bar, said support bar further extending exteriorly of said cross-section with one longitudinal edge of said support bar being outside said cross-section, and an electrically conductive bar affixed to the support bar along said one longitudinal edge and being in its entirety outside said cross-section.
 2. Apparatus according to claim 1 wherein said last-named conductive bar is provided with teeth, said apparatus further including means to reciprocate the support bar and last-named conductive bar crosswise of the loom.
 3. Apparatus according to claim 1 in which the support bar and last-named conductive bar have substantially the same thickness in directions transverse of their length and of the legs of said U-shaped cross-section. 